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GMATPrep - Practice Test #1 - DS - Please Help

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GMATPrep - Practice Test #1 - DS - Please Help

by dominate11 » Wed Feb 28, 2007 7:31 am
Any insight would be much appreciated...

7. In the triangle ABC above, what is the length of side BC? 1) Line segment AD has length 6 2) x=36 ( I was not sure how to include the example of the triangle)

9. On the sight seeing tour, the ratio of the number of women to the number of children was 5 to 2. What was the number of men on the sight seeing tour? 1) On the sight seeing tour, the ratio of the number of children to the number of men was 5 to 11. 2) The number of women on the sight seeing tour was less than 30.
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Source: — Data Sufficiency |
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Re: GMATPrep - Practice Test #1 - DS - Please Help

by gabriel » Sat Mar 03, 2007 8:54 am
dominate11 wrote:Any insight would be much appreciated...

7. In the triangle ABC above, what is the length of side BC? 1) Line segment AD has length 6 2) x=36 ( I was not sure how to include the example of the triangle)

9. On the sight seeing tour, the ratio of the number of women to the number of children was 5 to 2. What was the number of men on the sight seeing tour? 1) On the sight seeing tour, the ratio of the number of children to the number of men was 5 to 11. 2) The number of women on the sight seeing tour was less than 30.
for the first one i dont see a diagram.....

for the second one .... statement 1 along with the information in the question will give u the ratio of men:children:women... which is 22:10:25.... so this statement alone is not sufficient.... statement again does not give u any worthwhile information so this alone is not sufficient either... but take both the statement together and the only possible value of men that wuld satisfy both the given condition is 22 ... so the answer is C
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by Stacey Koprince » Sun Mar 11, 2007 10:52 pm
Hi, dominate - if you don't know how to post images, you can also just describe the triangle in text.
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triangle ABC

by snapplesf » Tue Mar 13, 2007 10:54 pm
Hi dominate11 ,

Assuming you figured out the triangle problem. if not,

if you work out the angles, you see that angles BAD=ABD
hence sides AD=BD=BC - hence A is sufficient.
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by hengirl03 » Mon Sep 08, 2008 11:18 pm
Would someone please post a detailed explanation to this problem? I'm still confused. Thanks!
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by Stacey Koprince » Tue Sep 09, 2008 5:59 am
they ask for a length, so statement 2 is not going to be useful - it gives us an angle only, and you can have a triangle of any size, teeny-tiny to huge, with those angles.

So, ACE.

AD is 6. <BAD is x. <BCD is 2x. <BCD is 2x. They want to know side BC.

<BDC is what's called an exterior angle of triangle BAD. You create this by taking any leg and just extending it out in a straight line. That exterior angle is always equal to the sum of the two opposite interior angles - in this case, angles BAD and ABD. So BAD + ABD = BDC. Fill in what you know. x + ABD = 2x. Solve. ABD = x.

So if ABD = x, it's the same angle as BAD. This means the sides opposite these angles are the same also. We know AD is 6, so BD is also 6.

Now look at the triangle on the right. We also have two identical angles there, so the two opposite sides are the same. One of those sides is BD (which we already know is 6) and the other side is BC, which we want to find. BC is also 6.

So statement 1 is sufficient. Answer is A.
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by hengirl03 » Tue Sep 09, 2008 10:16 am
Thanks Stacey!
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by canuckclint » Thu Sep 11, 2008 9:01 pm
For triangle ABD,
x + angleB + (180-2X) = 180
angleB - x = 0
angleB = x

The right triange is isoceles and you can go from there.
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by GMATGuruNY » Mon May 02, 2011 7:23 am
Image

To determine how the angles affect each other, PLUG IN.
As you plug in, be sure to satisfy the conditions in the problem as well as the rules of geometry.

Image

The drawings above show two valid combinations of angles.
In each case, AD = BD = BC.

Question rephrased: What is the length of AD or BD?

Statement 1: AD = 6.
Sufficient.

Statement 2: x=36.
No information about the any of the lengths.
Insufficient.

The correct answer is A.
Last edited by GMATGuruNY on Mon Feb 13, 2012 6:25 pm, edited 1 time in total.
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by kinji@BTG » Mon May 02, 2011 8:10 am
gabriel wrote:
dominate11 wrote:Any insight would be much appreciated...

9. On the sight seeing tour, the ratio of the number of women to the number of children was 5 to 2. What was the number of men on the sight seeing tour? 1) On the sight seeing tour, the ratio of the number of children to the number of men was 5 to 11. 2) The number of women on the sight seeing tour was less than 30.
for the second one .... statement 1 along with the information in the question will give u the ratio of men:children:women... which is 22:10:25.... so this statement alone is not sufficient.... statement again does not give u any worthwhile information so this alone is not sufficient either... but take both the statement together and the only possible value of men that wuld satisfy both the given condition is 22 ... so the answer is C
Even I reckon the answer is Option C that is both the statements are required. What is the OA.
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by ctdima » Thu Oct 06, 2011 6:40 pm
One thing I don't understand is why angle BAD is equal to x?
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by pappueshwar » Thu Mar 15, 2012 8:00 am
hi mitch!!

even i did nt understand as to how AD is = BD
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by GMATGuruNY » Thu Mar 15, 2012 8:35 am
In triangle BCD, since angle BDC = angle BCD = 2x, BD = BC.

To determine how the angles in the figure affect each other, PLUG IN.

Image

Top figure:
Let angle BAD = x = 10.
Then angle BDC and angle BCD = 2x = 2*10 = 20.

Triangle BCD:
Since angle BDC = angle BCD = 20, angle DBC = 140.

Triangle ABD:
Since angle BDC = 20, angle BDA = 160.
Since angle BAD = 10 and angle BDA = 160, angle ABD = 10.
Thus, AB = BD.

Putting it all together:
Since BD = BC, AB = BD = BC.

The same reasoning was applied to figure 2, in which I plugged in x=25.
The result was the same: AB = BD, implying that AB = BD = BC.
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by Campanella1989 » Wed Aug 07, 2013 4:37 pm
My question here is how do we know D lines in side AC?
Initially I chose A but after think about that, I chose E. I am reminded that never trust the Gmat figure.
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